The invention relates to a filter with an annular-shaped filter medium between end plates, with said filter medium being in the form of a filter cartridge, and mounted in a housing structure with a further functional part. In another aspect, the invention relates to a filter cartridge which is suitable for mounting in the filter of the invention.
Such filters are known. They are used, in particular, for filtering liquids, such as for filtering fuel for a fuel-burning engine. A filter of this type is disclosed, for example, in Biere et al., U.S. Pat. No. 5,547,565 (= EP 715,873). At the bottom of the housing, this filter has a discharge valve for water, which is contained in the fuel and which gradually separates and accumulates in the housing. A water sensor, which is likewise arranged at the bottom of the housing, determines the maximum allowable water level in the housing and signals the need to discharge the water from the fuel filter.
However, arranging the discharge valve and water sensor at the bottom of the housing of the fuel filter presupposes that there is sufficient space available there to install these elements in the engine compartment of the fuel-burning engine. The space conditions in motor vehicles are often greatly limited by other parts, after all. The chances of a practical integration of the fuel filter into the fuel-burning engine are therefore restricted by the described geometry of the water discharge and of the sensor. In particular, there must be enough space under the discharge valve in order to provide a collecting vessel for the water that drains off.